import operator
字典排序
1. 按字典值排序（默認為升序）
x = {1:2, 3:4, 4:3, 2:1, 0:0}
1. sorted_x = sorted(x.iteritems(), key=operator.itemgetter(1))
print sorted_x
[(0, 0), (2, 1), (1, 2), (4, 3), (3, 4)]
如果要降序排序,可以指定reverse=True
2. sorted_x = sorted(x.iteritems(), key=operator.itemgetter(1), reverse=True)
print sorted_x
[(3, 4), (4, 3), (1, 2), (2, 1), (0, 0)]
2. 或者直接使用list的reverse方法將sorted_x順序反轉(zhuǎn)
sorted_x.reverse()
3. 更為常用的方法是,用lambda表達式
3. sorted_x = sorted(x.iteritems(), key=lambda x : x[1])
print sorted_x
[(0, 0), (2, 1), (1, 2), (4, 3), (3, 4)]
4. sorted_x = sorted(x.iteritems(), key=lambda x : x[1], reverse=True)
print sorted_x
[(3, 4), (4, 3), (1, 2), (2, 1), (0, 0)]
包含字典dict的列表list的排序方法與dict的排序類似,如下：
x = [{'name':'Homer', 'age':39}, {'name':'Bart', 'age':10}]
sorted_x = sorted(x, key=operator.itemgetter('name'))
print sorted_x
[{'age': 10, 'name': 'Bart'}, {'age': 39, 'name': 'Homer'}]
sorted_x = sorted(x, key=operator.itemgetter('name'), reverse=True)
print sorted_x
[{'age': 39, 'name': 'Homer'}, {'age': 10, 'name': 'Bart'}]
sorted_x = sorted(x, key=lambda x : x['name'])
print sorted_x
[{'age': 10, 'name': 'Bart'}, {'age': 39, 'name': 'Homer'}]
5. sorted_x = sorted(x, key=lambda x : x['name'], reverse=True)
print sorted_x
[{'age': 39, 'name': 'Homer'}, {'age': 10, 'name': 'Bart'}]
